1. Field of the Invention
The present invention relates generally to the field of oil, gas and water wells and, more specifically, to a production casing tipper that cut a continuous vertical slot in well production casing.
2. Description of the Related Art
The prior art includes numerous examples of production casing perforators or cutters, but none of these inventions cuts a continuous vertical slot in the production casing through the use of a single, hydraulically-operated plunger. The prior art generally falls into three categories: casing cutters, single-hole punchers, and under reamers. The first category is represented by U.S. Pat. No. 1,777,713 (Braden, 1928); U.S. Pat. No. 2,049,450 (Johnson, 1936); U.S. Pat. No. 2,284,211 (Justice, 1942); U.S. Pat. No. 2,322,695 (Kinzbach, 1943); U.S. Pat. No. 2,525,007 (Worden et al., 1950); U.S. Pat. No. 2,725,936 (Hester, 1955); U.S. Pat. No. 2,859,943 (Chadderdon, 1958); U.S. Pat. No. 3,331,439 (Sanford, 1967); U.S. Pat. No. 3,419,077 (Sanford, 1968); U.S. Pat. No. 4,068,711 (Aulenbacher, 1978); and U.S. Pat. No. 4,646,826 (Bailey et al., 1987). The invention described in U.S. Pat. No. 5,732,770 (Beeman, 1998) is also a cutter, but it is specifically designed to address the situation where the cutter must pass through a relatively narrow inner diameter tubular prior to positioning in another tubular of wider inner diameter which is to be cut. These inventions are all designed to cut production casing or tubing horizontally rather than vertically.
The second category is exemplified by U.S. Pat. No. 2,328,782 (Bynum, 1943) and U.S. Pat. No. 2,753,935 (Fredd, 1956). The tools described in these patents are designed to punch a single hole in the production casing; they are not designed to cut a continuous vertical slot for any significant distance.
The third category—under reamers—relates to tools that are designed to pass out through the bottom of a pipe and drill a hole that is wider than the pipe through which the under reamer passed. Examples of these types of tools include U.S. Pat. No. 2,743,906 (Coyle, 1953) and U.S. Pat. No. 4,889,197 (Boe, 1989).
Several other inventions do not fall neatly within any of the three above categories. For example, the device described in U.S. Pat. No. 2,705,998 (Spang, 1955) is used to peel threads off couplings; it is not used to perforate a hole in the casing. The device described in U.S. Pat. No. 6,186,234 (Hailey, 2001) is not a production casing ripper or cutter, nor is it an under reamer. Instead, this tool is used to remove lining from the inside of tubing. U.S. Pat. No. 5,076,365 relates to a down hole cleaning system and method for removing debris located in a production zone below a packer in an oil well. These inventions are not similar to the present invention, but they do relate generally to tools that are used down hole.
There are three prior art devices that are somewhat similar to the present invention in that they cut vertical slots in casing, but none of these tools uses a plunger or hydraulics to do so, and all of them have limitations that do not exist in the present invention. These devices are described in U.S. Pat. No. 1,433,722 (Hinderliter, 1922); U.S. Pat. No. 1,776,025 (Hinderliter, 1930); U.S. Pat. No. 1,789,993 (Switzer, 1929); and U.S. Pat. No. 1,786,590 (Althausen, 1930). The Hinderliter inventions are designed to cut or rip the lower end of a casing sleeve out of a coupling or collar connecting the adjacent ends of a pair of casing sleeves. The Switzer tool has a rotating pizza cutter-type blade rather than a single blade, as in the present invention. The Althausen tool has to be lowered to the bottom of the well in order to disengage the blade.
As far as the inventor is aware, the only prior art device that cut vertically and that uses a plunger and hydraulics effectuate the cutting action is the invention described in U.S. Pat. No. 4,220,201 (Haul, 1980). This invention, however, does not create a continuous vertical slot; instead, it perforates the casing at evenly spaced intervals. This is due to the fact that the cutting blade is actually a cutter wheel with evenly spaced teeth extending radially from the center of the wheel. These teeth are what perforate the production casing.